Computer networks are prevalent among many enterprises and organizations. Typically, a network environment comprises a plurality of computerized devices interconnected to one another and sharing resources, such as, for example, through common access to one or more servers connected to the network. In many cases, some or even all of the devices in the network environment are simultaneously connected also to one or more external networks, such as the World Wide Web. As a result, any of the devices in the internal network environment are made much more susceptible to various security threats and attacks, in particular the proliferation of self-propagating malicious codes, also commonly known as “viruses” or “worms”. Once a device in the network becomes compromised, the infection can spread quickly to the remaining devices, causing irreparable harm.